This invention relates to machine tools wherein boring into a work piece is by using a boring bar. Although boring is conducted in various machine tools such as lathes, it is a Jig Bore Machine tool with which this invention is particularly concerned. However, the boring head herein disclosed can be employed in other machine tools having a turning spindle or work piece. In the particular case of jig bore machines, there is a quill that journals a boring head on a turning axis x along which the boring head is advanced and retracted. Axis x is usually vertical, in which case there is a horizontally adjustable table that supports and positions the work piece. The hole diameter to be bored in the work piece is determined by the adjusted eccentricity of the boring head, it being a general object of this invention to provide a precision boring head for jig bore machines and the like.
Heretofore, boring heads of the type under consideration have been subject to looseness inherent in the use of dovetail guides and screw positioning mens that require constant adjustment, for example. Also, wear and backlash have been problems. Therefore, it is an object of this invention to provide a boring head that is inherently accurate, wherein all adjustment errors are eliminated and wear and any backlash is simply adjusted out before the tool is used or as it is used over long periods of time.
In practice, boring heads are characterized by certain necessary features. The primary feature is the adjustment on a transverse axis c of the boring head per se, so that it is eccentrically parallel to the turning axis x of the turning spindle; and this is accomplished by a laterally shiftable carrier that is maintained in an erect condition to position the boring bar as required. Consequently, there can be looseness in the prior art shiftable engagements and also in the means that maintains the erect condition, it being an object of this invention to eliminate looseness in said shifting engagement and also in the maintainment of said erect condition.
Adjustment of the axis c relative to the axis x is accomplished by screw means operable between the body of the tool and the aforesaid shiftable carrier. Consequently, there can be looseness in the engagement of the screw means with respect to the body and also with respect to the carrier, it being an object of this invention to eliminte looseness in said engagement at both ends of the screw means.
During operation of a boring head of the type under consideration, vibration can occur and pressures are applied that will force the carrier out of position. Consequently, lock means is provided, it being an object of this invention to provide lock means to reliably secure the carrier in its adjusted position without any adverse affect on its adjustment and in a manner to prevent vibration and any maladjustment.
Heretofore, the usually accepted method of mounting boring bar carriers has resulted in rather complex and extended boring heads, it being an object of this invention to provide a close coupled combination of structural elements that reduces deflection by increasing strength in the use of the most efficient manufacturing methods that inherently result in tight close fitting parts and elements of the tool and which are adjustable within the required range of adjustment and all without looseness or any backlash. All looseness and backlash are inherently minimal in this boring head, and that which may be detected is readily and simply removed by adjustment, including any wear that may take place in time.
It is also an object of this invention to integerate the aforesaid features of this boring head, so that it is closely coupled to the turning spindle, or machine tool stock, to which it is attached. In jig bore machines there is an adapter that secures the boring head to the spindle which is advanced and retracted by the quill. Machining accuracy is attained by the close coupled features of this boring head, wherein the parts and elements are closely integrated, so as to eliminate deflection from the adjusted position thereof. Adjustment is by an accessible vernier micrometer, in which backlash is removed.
The foregoing and various other objects and features of this invention will be apparent and fully understood from the following detailed description of the typical preferred form and application thereof, throughout which description reference is made to the accompanying drawings.